1. Field of the Invention
The present invention relates to e production scheduling, more specifically to a method and apparatus for a progress management assistance suitable to make a production schedule according to actual results step by step.
2. Description of the Prior Art
(1) As a conventional technique, a progress management assistance apparatus reads actual result data, modifies scheduled data according to the actual results, and allocates lots whose data have been modified using the same algorithm as the schedule has been formed.
(2) As another conventional technique disclosed in a specification of Japanese Patent Laid-Open Publication No. 63-24443, a start time and a finish time of an event (corresponding to a lot in this invention) are expressed by a relational expression in a network to successively determine a start time or a finish time of another event relating to each event.
The above two conventional techniques have the following disadvantages.
In the conventional technique (1), time data of each lot is expressed with numerical values but no relation between the data is explicitly described. Thus, it is necessary to modify time data of many of lots in order to keep an order of lots and production facilities used for each lot unchanged before and after an addition of the actual results. Therefore, this technique has poor efficiency.
In the conventional technique (2) disclosed in the specification of Japanese Patent Laid-Open Publication No. 63-24443, a start time and a finish time are expressed by a relational expression in a network, as well. However, if this technique is applied to a production scheduling, it is impossible to comply with a case where an idle period exists between lots.
An object of this invention is to solve the above problems retained in the conventional techniques, and to determine efficiently a new schedule with no change in an order of the lots and used facilities before and after an addition of an actual result.